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Extremely touch brakes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jghake, Mar 1, 2013.

  1. Jghake

    Jghake Junior Member

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    My 2009 Pkg 6 just started having VERY touchy brakes last night. It's almost as if there is a point where the brakes just lock up instead of a gradual regen, then gradual braking. My wife has been the primary driver for the last few days and she said the traction control light flashes briefly for yesterday but the brakes seemed fine until I drove it last night.

    Does anyone have any ideas? I'm very car savy (I just replaced the fuel pump in my Explorer) so I would like to try to keep it out of the dealer if possible.

    Thanks guys.
     
    #1 Jghake, Mar 1, 2013
  2. edthefox5

    edthefox5 Senior Member

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    We know exactly whats causing that. You must not have had the car long. Because the friction brakes don't get alot of heavy use due to regen assist the rotors get very corroded. Look at them. They get very rusted and pitted. That rusted surface makes it very grabby on the pads especially if it has just rained. This condition is greatly exacerbated if the car is not garaged.

    The fix is continued maintenance. This is done by getting up to speed and with no one in front or back put the trans in neutral which shuts the engine off and removes regen. You are then on friction brakes only. Apply firm pressure to the brake pedal. Do that a few times a day at first. You can even slap it into neutral and apply the brakes while coming to a light a few times a day.
    This friction braking only removes the top very crusty surface of the rotors.

    Btw your question is the number 2 question on this forum. The number one is the 12 volt battery issues.
     
    #2 edthefox5, Mar 1, 2013
  3. Jghake

    Jghake Junior Member

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    Thank you for answering my question so promptly. I am sorry if I have asked the same question that others ask over and over again. I am new to Prius ownership, we have only had the car for a few weeks. I will take a look at this tonight. Would it be better to just remove the rotors and have them turned?

    I also apologize for the triple post. I use Tapatalk for the iPhone and it would appear that it did work when it told me it didn't. I have tried to figure out how to delete the other two posts but I do not appear to have rights to do so.
     
    #3 Jghake, Mar 1, 2013
  4. edthefox5

    edthefox5 Senior Member

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    OK your welcome. Not necessary to remove the rotors as that is a pain but they may be really bad. Take a picture of the rotor and post it. Lets see how bad it is.

    Most new used Gen II owners have to replace the little 12 volt battery in the trunk too. Usually because the car sat on the car lot for a while and killed the battery and needed to be jumped. If that little battery sits dead for quite a while it ruins the battery. Do all you can do to not have to jump start a Prius. Can be very expensive if jumped improperly.

    Its about $250 to replace that little 12 volt at the dealer. There's alot of DIY options though but all around $200.

    Here's a simple way to check that battery:

    Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

    Note there are 3 voltage samples there. Please post back all 3.
    Unloaded
    Loaded (this is the important one. I bet your car is way below 12 volts)
    Ready
     
    #4 edthefox5, Mar 1, 2013
  5. fuzzy1

    fuzzy1 Senior Member

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    Shouldn't we be listing this as a likely cause, not as the definitive cause?

    Between the lack of a gradual regen before this lockup occurs, and the different rusted brake behavior on my old car, my confidence in this diagnosis is much weaker than yours.
     
    #5 fuzzy1, Mar 1, 2013
  6. Jghake

    Jghake Junior Member

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    I will start with looking at this because I think I remember seeing a sheen of rust on the rotors but I am open to any suggestions as to what to look into.
     
    #6 Jghake, Mar 1, 2013
  7. Jghake

    Jghake Junior Member

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    My battery voltages are:
    ACC: 12.5V
    Load: 12.3V
    Ready: 14.1V

    Here are pictures of my rotors.

    [​IMG]


    [​IMG]
     
    #7 Jghake, Mar 1, 2013
  8. fuzzy1

    fuzzy1 Senior Member

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    Battery appears fine, though this test is best done after the car has been shut down several hours or overnight. The voltage (ACC and Load) will be artificially high for a while after the car has been run. Ready voltage is really the inverter output voltage, not a useful battery level.

    And I wish the brakes on my old nonhybrid where that clean.

    How many miles on this car? Do the brakes have any squeal such as when the pads/shoes are worn out and down to the metal warning indicator? On a past car, I once wore down a rear brake shoe too far, and it went from a slight annoyance on one trip segment, to a very serious grabbing problem on the very next trip.

    Any other ideas from the group?
     
    #8 fuzzy1, Mar 1, 2013
  9. Jghake

    Jghake Junior Member

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    The car has 93k, and had its 90k by the previous owners at the Toyota dealer just before they traded it in. I have all records since new available on Toyota.com as it appears the previous owners bought it new and serviced it at the dealer only. There is even oil change records from new. The brakes were at 75% front and back. I think it was 9mm/12mm on the front and 3mm/4mm on the back. We aren't getting any grinding sounds and my wife said it stopped giving her problems on her way home from work. It was very touchy last night and my wife kept yelling at me to stop slamming on the brakes... I just ignored her ;) and told her it was probably because I was wearing my sandals (to lazy to put shoes on). She texted me on her lunch to say it was giving her problems too.

    A new battery in November of last year at the dealer as well. I did the voltage check when I got home from work about an hour and a half after she got home herself.

    Thanks for all of your help guys. If there is anything you guys want me to check let me know. I'll probably go grab dinner here in a bit so I'll report back how it drove.
     
    #9 Jghake, Mar 2, 2013
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